Technical Field
The present disclosure relates to monomers and cyclocopolymers having an amino acid methionine-based structure as well as methods for their synthesis and preparation. Additionally, the present disclosure relates to applications of these monomers and cyclocopolymers as inhibitors of metallic corrosion.
Description of the Related Art
The “background” description provided herein is for the purpose of generally presenting the context of the disclosure. Work of the presently named inventors, to the extent it is described in this background section, as well as aspects of the description which may not otherwise qualify as prior art at the time of filing, are neither expressly or impliedly admitted as prior art against the present invention.
Butler's cyclopolymerization protocol [Butler G B (1992) Cyclopolymerization and cyclocopolymerization, Marcel Dekker, New York, N.Y., USA; and Kudaibergenov S, Jaeger W, Laschewsky A (2006) Polymeric betaines: Synthesis, characterization, and application. Adv. Polym. Sci., 201:157-224; and Singh P K, Singh V K, Singh M (2007) Zwitterionic polyelectrolytes: A review. E-Polymers 030:1-34; and Jaeger W, Bohrisch J, Laschewsky A (2010) Synthetic polymers with quaternary nitrogen atoms—synthesis and structure of the most used type of cationic polyelectrolytes. Prog. Polym. Sci 35:511-577—each incorporated herein by reference in its entirety] involving diallylammonium salts has led to a plethora of industrially significant pyrrolidine ring-embedded cyclopolymers whose architecture is considered to be the eighth most important structural type [Butler G B (2000) Cyclopolymerization. J. Polym. Sci. Part A: Polym. Chem 38:3451-3461; and McGrew F C (1958) Structure of synthetic high polymers. J. Chem. Educ 35:178-186. —each incorporated herein by reference in its entirety]. Butler's cyclopolymer poly(diallyldimethylammonium chloride) has numerous publications and patents (>1000) and over 35 million pounds of it alone are sold per year for water purification and personal care formulations. Numerous diallylammonium monomers have also been copolymerized with SO2 to give value added products [Ali S A, Al-Hamouz O C S (2012) Comparative solution properties of cyclocopolymers having cationic, anionic, zwitterionic and zwitterionic/anionic backbones of similar degree of polymerization. Polymer 53:3368-3377; and Abu-Thabit N Y, Kazi I W, Al-Muallem H A, Ali S A (2011) Phosphonobetaine/sulfur dioxide copolymer by Butler's cyclopolymerization process. Eur. Polym. J 47:1113-1123; and Ali S A, Umar Y, Abu-Sharkh B F, Al-Muallem H A (2006) Synthesis and comparative solution properties of single-, twin-, and triple-tailed associating ionic polymers based on diallylammonium salts. J. Polym. Sci. Part A Polym. Chem 44:5480-5494. —each incorporated herein by reference in its entirety].
One objective in the field is to examine the efficacy of functional motifs of trivalent amine and sulfide in a polymer backbone in arresting metal corrosion. Inhibition of metal corrosion by organic inhibitors is influenced by the presence of heteroatoms whose efficacies are known to increase in the order O<N<S<P [Kiani M A, Mousavi M F, Ghasemi S, Shamsipur M, Kazemi S H (2008) Inhibitory effect of some amino acids on corrosion of Pb—Ca—Sn alloy in sulfuric acid solution. Corros. Sci 50:1035-1045. —incorporated herein by reference in its entirety]. The inhibitor molecules interfere with anodic and cathodic reactions occurring on the metal surfaces, and thus arrest or minimize the corrosion process [Revie W, Uhlig H H (2008) Corrosion and Corrosion Control: An Introduction to Corrosion Science and Engineering, Wiley-Interscience, NY, USA; and Sastri V S (1998) Corrosion Inhibitors, Principles and Application, John Wiley and Sons, USA—each incorporated herein by reference in its entirety]. The greater polarizability of the lone pair of electrons in the third period elements makes them better inhibitors as a result of formation of coordinate-type bonds to cover and safeguard the metal surface.
Available at low cost, the non-toxic amino acid methionine is attractive as a green inhibitor of mild steel corrosion since it contains three important heteroatoms: N, O and S. The methionine at a concentration of 25 ppm has been shown to impart 47% inhibition of mild steel corrosion in 0.1 M HCl at 25° C. [Zor S, Kandemirli F, Bingul M (2009) Protection of Metals and Physical Chemistry of Surfaces, Pleiades Publishing Ltd, Moscow, Russia. —incorporated herein by reference in its entirety]. At respective concentrations of 149, 165, and 181 ppm of methionine, methionine sulfoxide and methionine sulfone, the inhibition efficiency (IE) against copper corrosion in 1 M HNO3 have been determined to be 79%, 85% and 88% [Khaled K F (2010) Corrosion control of copper in nitric acid solutions using some amino acids—A combined experimental and theoretical study. Corros. Sci 52:3225-3234. —incorporated herein by reference in its entirety]. In corrosive environments of 1 M HCl at 30° C. and 2 M HCl at 25° C. containing 149 ppm of methionine and 1000 ppm of glutaraldehyde-methionine condensation product, respectively, the corresponding IE of mild steel corrosion are reported to be 89% and 84% [Shanmugasundaram P, Sumathi T, Chandramohan G, Ramesh-Bapu G N K (2013) Corrosion inhibition study of 1062 grade a-low carbon steel in 1M HCl by L-methionine- weight loss, ICP-OES and SEM-EDX studies. Int. J. Curr. Res 5:2183-2191; and Rajappa S K, Venkatesha T V (2002) New condensation products as corrosion inhibitors for mild steel in a hydrochloric acid medium. Ind. J. Eng. Mater. Sci. 9:213-217. —each incorporated herein by reference in its entirety].
The use of methionine as a green corrosion inhibitor has thus achieved modest inhibition efficiencies. The industry demands much greater efficacies, on the order of 99% or more. Corrosion is a large concern in terms of cost, safety, health and environmental aspects and has become an increasing priority in both industry and society [Panah N B, Payehghadr M, Danaee I, Nourkojouri H, Sharbatdaran M (2012) Investigation of corrosion performance of epoxy coating containing polyaniline nanoparticles. Iran Polym J 21(11):747-754; and Amirshaqaq N, Salami-Kalajahi M, Mandavian M (2014) Corrosion behavior of aluminum/silica/polystyrene nanostructured hybrid flakes. Iran Polym J 23(9):699-706—each incorporated herein by reference in its entirety]. Even an improvement of 1% efficacy translates into a considerable savings. Polymers typically undergo stronger adsorption onto metal surface because of multiple anchoring sites, and thus exhibit better inhibition efficiencies than their monomeric analogs [Ulman, R. (1964) in Encyclopedia of Polymer Science and Technology; Vol. 1, (Eds: Mark, H. F.; Gaylord, N. G.; Bikales, N. M.), Interscience, New York, USA; and Annand R R, Hurd R M, Hackerman N (1965) Adsorption of Monomeric and Polymeric Amino Corrosion Inhibitors on Steel. J. Electrochem. Soc 112:138-144; and Bacskai R, Schroeder A H, Young D C (1991) Hydrocarbon-soluble alkaline/formalin/formaldehyde oligomers as corrosion inhibitors. J. Appl. Polym. Sci 42:2435-2441. —each incorporated herein by reference in its entirety].
In view of the forgoing, one object of the present disclosure is to provide cyclopolymers containing residues of methionine keeping intact the integrity of its sulfide motifs and unquenched nitrogen valency (i.e. a trivalent N with its lone pair of electrons). This includes the synthesis of the potentially green novel monomer as well as the first time use of Butler's cyclopolymerization protocol for the formation of its cyclocopolymers having residue of essential amino acid methionine in each repeating unit. In addition to the monomers, cyclopolymers and methods for their preparation, the present disclosure further aims to provide methods for evaluating their efficacies in arresting metal corrosion, such as mild steel corrosion in 1 M HCl. A further aim of the present disclosure, is to provide a method for preventing or inhibiting metal corrosion comprising treatment with the cyclopolymers as well as metallic materials comprising the cyclopolymers in or on said metallic materials.